Chair for a concrete lifting anchor

ABSTRACT

A chair for supporting an edgelift anchor for use in lifting a concrete component, said anchor comprising a head portion engagable with a clutch of a lifting system, and a body portion for embedment with the concrete component, wherein the chair has surfaces configured for supporting the edgelift anchor relative to a casting surface during casting of the concrete component.

FIELD OF THE INVENTION

This invention relates to a chair for a concrete component lifting anchor and, more particularly but not exclusively, to a height-adjustable chair for an edgelift anchor.

BACKGROUND OF THE INVENTION

It is known to lift a concrete panel by way of an edgelift anchor embedded within a side edge of the concrete panel during casting of same. Typically, the edgelift anchor is held in place during casting by supporting the anchor on a sideform used for casting the concrete panel. However, the applicant has identified that edgelift anchors supported in this way are difficult to support adequately, and are prone to being embedded incorrectly relative to the concrete panel, particularly due to movement of the anchor under its own weight, and due to movement of the sideform.

Concrete panels may also be lifted by a facelift anchor embedded within a face of the concrete panel during casting. The applicant has determined that existing apparatus for supporting a facelift anchor during casting of a concrete panel typically lack the ability to conveniently adjust the height of the anchor relative to the concrete panel. Accordingly, the anchor may be set to an incorrect depth within the concrete component.

Examples of the invention seek to solve, or at least ameliorate, one or more disadvantages of previous apparatus for supporting lifting anchors during casting of concrete components.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, there is provided a chair for supporting an edgelift anchor for use in lifting a concrete component, said anchor comprising a head portion engagable with a clutch of a lifting system, and a body portion for embedment with the concrete component, wherein the chair has surfaces configured for supporting the edgelift anchor relative to a casting surface during casting of the concrete component.

Preferably, the chair has first and second parts configured to support the anchor relative to the casting surface at a first height using the first part on its own, or in conjunction with the second part to provide a range of further heights. More preferably, the first and second parts are arranged so as to be used in conjunction in one configuration to support the anchor at a second height relative to the casting surface, and in another configuration in which the second part is inverted to support the anchor at a third height relative to the casting surface.

Preferably, the chair is configured to support the anchor such that a longitudinal axis of the anchor is substantially parallel to the casting surface.

In one example, the chair is provided in combination with an edgelift anchor supported by the chair, wherein the body portion of the anchor has a plane oriented substantially parallel to the casting surface.

In another example, the chair is provided in combination with an edgelift anchor supported by the chair, wherein the body portion of the anchor has a plane oriented substantially perpendicular to the casting surface.

Preferably, the head portion of the anchor has a plane oriented substantially perpendicular to the casting surface.

In accordance with another aspect of the present invention, there is provided a chair for supporting an anchor for use in lifting a concrete component, said anchor comprising a head portion engagable with a clutch of a lifting system, and a body portion for embedment with the concrete component, wherein the chair has first and second parts configured to support the anchor, during casting, relative to the casting surface at a first height using the first part on its own, or in conjunction with the second part to provide a range of further heights.

Preferably, the first part has a support for the anchor, and the second part is arranged for supporting the first part relative to the casting surface, and wherein the second part is able to be interchanged with either a different second part or the same second part when inverted to selectively support the anchor at a range of different heights relative to the casting surface. More preferably, each different second part is able to selectively support the anchor at two different heights relative to the casting surface by inverting the second part. Even more preferably, each second part is marked on opposite sides to represent a height at which the anchor is supported when the second part is used in conjunction with the first part, with the second part being in a non-inverted and/or an inverted configuration.

Preferably, the chair is adapted for supporting a void former when fitted to the anchor. More preferably, the chair has one or more arms which extend to directly support the void former.

Preferably, the chair is adapted to support a reinforcement mesh of the concrete component. More preferably, the chair includes an insert for supporting the reinforcement mesh. Even more preferably, the chair includes a range of inserts which are interchangeable for supporting the reinforcement mesh at different heights relative to the anchor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described, by way of non-limiting example only, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a lifting anchor having a collar;

FIG. 2 is a perspective view of the anchor of FIG. 1, shown with an associated chair;

FIG. 3 is a perspective view of the anchor, shown with the chair fitted thereto;

FIG. 4 is a side view of the anchor, with the chair fitted thereto;

FIG. 5 is a top view of the anchor, with the chair fitted thereto;

FIG. 6 is a perspective view of the chair shown in isolation, in a deconstructed condition;

FIG. 7 is a perspective view of an edge of a concrete component with the anchor embedded therein;

FIG. 8 is a head portion end perspective view of another anchor, shown in place relative to a chair for supporting the anchor;

FIG. 9 is a body portion end perspective view of the anchor and chair shown in FIG. 8;

FIG. 10 is a top view of the anchor and chair shown in FIGS. 8 and 9;

FIG. 11 is a side view of the anchor and chair shown in FIGS. 8 to 10;

FIG. 12 is a head portion end view of the anchor and chair shown in FIGS. 8 to 11;

FIGS. 13 a to 13 d show various views of the anchor of FIGS. 8 to 12, shown in place relative to a chair for supporting the anchor, the chair also supporting a tension bar of the anchor;

FIG. 14 is a perspective view of the chair shown in FIGS. 13 a to 13 d, shown with a pair of inserts for supporting a reinforcement mesh of the concrete component;

FIG. 15 is a perspective view of the chair of FIG. 14, shown with the inserts in place and supporting a reinforcement mesh;

FIG. 16 is a side view of the chair of FIG. 14 with inserts in place, supporting the reinforcement mesh;

FIG. 17 is a perspective view of the chair of FIG. 14 shown with an interchangeable insert of a different height;

FIG. 18 is a side view of the chair and insert of FIG. 17, shown supporting the reinforcement mesh at a different height relative to the anchor;

FIGS. 19 a to 19 d are perspective, side, top and end views of a chair supporting an anchor, together with a void former fitted to the anchor;

FIGS. 20 a to 20 d are perspective, side, top and end views of an alternative chair shown supporting an anchor, together with a void former fitted to the anchor; and

FIGS. 21 a to 21 d are perspective, side, top and end views of a further alternative chair shown supporting an anchor, together with a void former fitted to the anchor.

DETAILED DESCRIPTION

With reference to FIG. 1, there is shown an anchor 10 for use in lifting a concrete component 12. The anchor 10 shown is in the form of an edge lift anchor, however it will be appreciated by those skilled in the art that alternative examples may be used with other types of anchors such as, for example, a face lift anchor.

The anchor 10 comprises a single length of wire 14 bent to form a head portion 16 engagable with a clutch of a lifting system, and a body portion 18 for embedment with the concrete component 12. The wire 14 is bent such that opposed legs 20, 22 of the body portion 18 extend in a plane substantially perpendicular to a plane of the head portion 16. By virtue of the wire 14 being bent in this way, the anchor 10 is able to be arranged such that the opposed legs 20, 22 lie in a plane substantially parallel to a central plane of the concrete component 12, while the head portion 16 is oriented substantially perpendicularly to the central plane of the concrete component 12. Advantageously, this enables the anchor 10 to be located lower in the concrete component 12 to facilitate edge lifting of the concrete component 12, while facilitating a broad spread of the opposed legs 20, 22 within the concrete component 12.

As the legs 20, 22 are spread outwardly from a central axis 24, the load applied to the anchor 10 is distributed through a larger region of the concrete component 12 than is possible with a typical concrete anchor having parallel legs. Accordingly, this reduces the likelihood of the concrete component 12 failing during lifting, as a large region of the concrete component 12 must fail for the anchor 10 to be torn out during lifting. Each of the legs 20, 22 may be formed with a wave-like configuration by incorporating a series of ripple bends to provide additional anchorage of the anchor 10 within the concrete component 12. Advantageously, the ripple bends prevent the legs 20, 22 from being withdrawn from the concrete, by applying compression to the concrete during lifting. As such, the opposed legs 20, 22 are able to provide the same function as ancillary tension bars which have been used in existing lifting anchors.

To achieve the perpendicular configuration, the head portion 16 in the example shown is twisted through an angle of 270 degrees relative to the body portion 18 about the central axis 24 of the anchor 10. In alternative anchors, to achieve a perpendicular configuration the head portion may be twisted through an angle of 90 degrees (or, more generally, an angle of 90+180x, where x is a whole number) relative to the body portion 18 about the central axis 24 of the anchor 10. The central axis 24 is in the plane of the head portion 16. In this way, the plane of the head portion 16 is perpendicular to the plane of the body portion 18.

It will be understood that in alternative examples, the body portion 18 may be rotated about the central axis 24 relative to the head portion 16 such that the plane of the body portion 18 is out of the plane of the head portion 16 by an angle other than 90 degrees. In particular alternatives, this angle may be approximately 60, 45, 30 or 15 degrees, as may be appropriate depending on the shape and/or orientation of the concrete component 12.

The head portion 16 of the anchor 10 may also be tilted upwardly/downwardly out of the plane of the legs 20, 22. This tilting of the head portion 16 may be achieved by bending the anchor on site, and may be advantageous when using the anchor 10 to lift concrete components having angled edges. In particular examples, the edge of the concrete panel may be at an angle of 9 degrees, 15 degrees, 22.5 degrees, 30 degrees or 45 degrees to a plane perpendicular to the central axis 24, and the head portion 16 may be bent relative to the legs 20, 22 at a corresponding angle.

The anchor 10 includes a collar 26 adapted to fit around the head portion 16, as shown in FIG. 1. The collar 26 forms abutment shoulders 28 at upper and lower locations of the head portion 16 for cooperation with a body of the clutch to limit clutch rotation relative to the anchor 10.

More specifically, the collar 26 includes an attachment portion 58 for attaching the collar 26 to the lifting anchor 10, and an abutment portion 60 adapted to provide a clutch abutment surface for limiting rotation of a clutch relative to the lifting anchor 10. The attachment portion 58 is arranged for attaching the collar 26 to the head portion 16 of the lifting anchor 10. When the collar 26 is fitted to the anchor 10, the clutch abutment surface is formed as an abutment shoulder 28 adjacent each side of the head portion 16 for limiting rotation of the clutch about an eye 62 of the head portion 16, in both directions of rotation. The collar 26 may include a gap 64 between the shoulders 28 which coincides with the eye 62 of the head portion 16 to allow passage of the clutch through the eye 62.

The collar 26 is generally C-shaped, including a pair of clasps for coupling to opposed wire lengths of the head portion 16, with a connecting strip 66 between the clasps. Each clasp terminates in a tab 68 which secures the collar 26 to the head portion 16 by way of a hard press fit. The abutment portion 60 is formed by an edge of the collar 26, at each of the clasps.

The collar 26 includes a pair of shear bars 30, 32 attached to the collar 26. The shear bars 30, 32 extend generally perpendicularly to the central axis 24, generally in the plane of the body portion 18. These shear bars 30, 32 assist in preventing shear failure of the concrete component 12 during lifting, and provide improved anchorage of the anchor 10 within the concrete component 12. Each of the shear bars 30, 32 is formed in a generally wave-like shape, with lateral oscillations 34 in a direction generally perpendicular to the central axis 24 of the anchor 10. A second one of the shear bars 30 is located under a first one of the shear bars 32, and is reversed such that the second shear bar 30 is substantially a mirror image of the first shear bar 32 when viewed from an end of the anchor 10. The shear bars 30, 32 may be positively held in place relative to the head portion 16 by engagement of the shear bars 30, 32 within grooves 36 formed in the collar 26. The grooves 36 formed on opposite sides of the collar 26 may be formed in a correspondingly offset configuration so as to positively locate the shear bars 30, 32 in the arrangement shown. Alternatively, the shear bars 30, 32 may be fixed relative to the head portion 16 by spot welding of the shear bars 30, 32 to the collar 26.

The applicant has determined that the collar 26 is particularly suited for use in providing a concrete component lifting anchor formed of bent wire with clutch abutment surfaces for limiting rotation of a clutch relative to the lifting anchor. This is because there is not the same ability in providing anchors formed of bent wire with shoulders as there is with anchors cut from plate. However, it is possible for collars formed in accordance with other examples of the present invention to be used with anchors formed from plate, and such collars may provide various advantages over cut abutment shoulders. In particular, using a collar according to an example of the present invention provides the ability to interchange collars to change the size/shape of abutment shoulders, and provides a convenient way to attach shear bars to the anchor.

The collar 26 is preferably formed of metal, in particular from folded steel. In other examples, the collar may be formed from plastic.

Returning to the actual anchor itself, the length of wire 14 from which the anchor 10 is formed may be a length of metal bar which is bent to form the anchor 10. The length of metal bar may be drawn from a coil. Advantageously, by virtue of the anchor 10 being formed from metal bar, material wastage is minimised, and the anchor 10 is manufactured in a particularly cost-effective manner.

In particular, the head portion 16 is formed by bending the metal bar around a forming piece, the forming piece being a pin having a size corresponding to the size of a clutch portion to pass through the head portion 16. By virtue of this forming process, any variation in the dimensions (particularly the diameter) of the metal bar will not alter the size of the aperture in the head portion 16. Accordingly, it is possible to provide a superior tolerance for an effective, rigid coupling between the clutch and the anchor, thus avoiding a sloppy coupling between the anchor and the clutch. In other words, variation in the wire does not affect quality of engagement between the anchor and the clutch.

Also, by virtue of the anchor 10 being formed of from round cross-section metal bar, there is a single point of contact between the clutch portion and the anchor 10, avoiding the problems associated with skewed prior art anchors cut from metal plate which tend to transfer undesirable forces to the concrete component 12.

With reference to FIG. 2, the anchor 10 forms part of an anchor assembly 38 which includes a chair 40. The chair 40 comprises a first, upper, part 44 and a second, lower, part 46 which are fitted together, with the first part 44 having clips 48 for holding the anchor 10 in place relative to the chair 40, as shown in FIGS. 3 to 5. FIG. 6 shows a detailed view of the first part 44 and the second part 46 in isolation. As the body portion 18 is in a plane perpendicular to the plane of the head portion 16, when in situ the opposed legs 20, 22 do not extend below the head portion 16, thus allowing the anchor 10 to be mounted in a relatively low position within the concrete component 12, while ensuring the opposed legs 20, 22 are embedded inside the concrete component 12. More particularly, the chair 40 is arranged for supporting the anchor 10 within the concrete component 12 during casting, with the plane of the body portion 18 coplanar or oriented substantially parallel to a central plane of the concrete component 12.

By virtue of the plane of the body portion 18 being coplanar with or substantially parallel to a central plane of the concrete component 12, it is possible for the body portion 18 to be located at or within a neutral axis of the concrete component 12 so as to avoid having the anchor embedded in regions of the concrete component 12 which are under high compression and/or tension during lifting. This may assist in avoiding failure of the concrete component 12 during lifting, and may enable lifting of concrete panels at a stage more premature (relative to the time of casting) than is required for lifting using existing concrete anchors.

Furthermore, the feature of the plane of the body portion 18 being coplanar with or substantially parallel to the central plane of the concrete component 12 enables the anchor to be used with concrete panels much thinner than is required for lifting using existing concrete anchors which extend transversely across a substantial portion of the thickness of the panel.

FIG. 7 shows an edge of a concrete component 12 in which the anchor 10 is embedded. A void 56 is formed around the head portion 16, and facilitates engagement of a clutch with the anchor 10 for lifting of the concrete component 12. Although in this drawing the anchor 10 is shown as being mounted in a central part of the concrete component 12, it will be appreciated by those skilled in the art that the anchor 10 may be mounted within the concrete component 12 in a lower location such that the plane of the body portion 18 is below the central plane of the concrete component 12.

Advantageously, the chair 40 has surfaces in the form of the clips 48 and feet 70 configured for supporting the anchor 10 relative to a casting surface during casting of the concrete component 12. Where the chair 40 is used including its second part 46, the surfaces configured for supporting the anchor also include upper and lower surfaces 72, 74 of the foot spacers 76. The first and second parts 44, 46 are configured to support the anchor 10 relative to the casting surface at a first height using the first part 44 on its own, or in conjunction with the second part 46 to provide a range of further heights. This is achieved by supporting the anchor 10 using the first part 44, the feet 70 of which sit directly on the casting surface, or by using the second part 46 in the manner shown in FIGS. 3 and 4. The first and second parts 44, 46 may be used in conjunction in this configuration to support the anchor at a second height relative to the casting surface, and in another configuration in which the second part 46 is inverted so as to support the anchor 10 at a third height relative to the casting surface. As can be seen in FIGS. 2 and 3, the second part 46 is marked on opposite sides to indicate a height at which the anchor 10 is supported when the second part 46 is used in conjunction with the first part 44, with the second part being in a non-inverted and/or an inverted configuration. In particular, the markings indicate the height at which the anchor 10 is supported when the respective side of the second part 46 faces upwardly.

As can be seen in the side view of FIG. 4, the chair 40 is configured to support the anchor 10 such that the longitudinal central axis 24 of the anchor 10 is substantially parallel to the casting surface. In this way, the anchor 10 is oriented correctly for lifting of the concrete component 12 by the head portion 16 after casting. In the example shown in FIGS. 3 to 5, the anchor 10 is supported by the chair 40 such that the body portion 18 of the anchor 10 has a plane oriented substantially parallel to the casting surface. In contrast, in the example shown in FIGS. 8 to 12, the anchor 10 is supported by the chair 40 such that the body portion 18 of the anchor 10 has a plane oriented substantially perpendicular to the casting surface. The anchor 10 shown in FIGS. 8 to 12 is a typical edgelift anchor formed from plate by a process of cutting, however it may be supported by a chair 40 formed in accordance with the present invention in the manner shown. Like features are denoted with like reference numerals.

As the anchor 10 shown in FIGS. 8 to 12 is cut from plate and is substantially planar such that the head portion 16 and body portion 18 rest in the same plane, it is necessary for the plane of the body portion 18 to be substantially perpendicular to the plane of the casting surface in order for the head portion 16 to have the correct orientation for lifting of the concrete component 12. Accordingly, the first part 44 is formed with slots 78 so as to support the anchor 10 in this perpendicular orientation. The first part 44 is also provided with holders 80 for holding the shear bars 30, 32 in configuration. In this way the shear bars 30, 32 are held in place sufficiently without spot welding to the collar 26 as in the example shown in FIGS. 1 to 7.

Although FIGS. 8 to 12 do not show a second part 46 of the chair 40, a second part 46 similar to the one shown in FIGS. 2 to 6 may be used.

The casting surface may be a ground surface against which the concrete component is formed, or an underlying surface (eg. of another concrete component) which is used as a surface for forming the concrete component in which the anchor 10 is to be embedded.

Advantageously, the chair 40 provides an apparatus which enables convenient height adjustment of the anchor 10 relative to the casting surface so that it can be embedded at a desired location within the concrete component 12. The second part 46 is able to be interchanged with other second parts to provide different heights relative to the casting surface. Each second part 46 may be configured asymmetrically in a manner similar to the second part 46 shown in FIGS. 2 to 6, so as to provide two different heights relative to the casting surface by inversion.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.

In particular, although the example anchor depicted in the drawings has an angle between the plane of the legs and the plane of the head portion of approximately 90 degrees, it will be understood that in alternative examples the angle between the plane of the legs and the plane of the head portion may take other values, for example 60, 45, 30 or 15 degrees. This angle may be dictated by the shape and/or orientation of the concrete component.

With reference to FIGS. 13 a to 13 d, the anchor 10 cut from metal plate material may be provided with a tension bar 82, and the chair 40 may have angled clips 84 for supporting the tension bar 82. As shown in these drawings, the anchor 10 may be provided with only a single shear bar 30, and the chair 40 may be provided with only a single set of holders 80 for holding the shear bar 30.

With reference to FIGS. 14 to 18, the chair 40 may be provided with one or more inserts 86 for supporting a reinforcement mesh 88 of the concrete component. The inserts 86 may be shaped so as to be inserted into the feet 70 of the chair 40, as shown. With reference to FIGS. 15 and 16, when the inserts 86 are mounted in place on the chair 40, upper surfaces 90 are arranged so as to support the reinforcement mesh 88. As can be seen, the inserts 86 are arranged such that the upper surfaces 90 support the reinforcement mesh 88 approximately midway between the legs of the anchor 10. However, in some circumstances, it may be desirable to support the reinforcement mesh 88 at a different location relative to the anchor 10, and the inserts 86 may be interchangeable with one or more other inserts 92 as shown in FIGS. 17 and 18. The interchangeable inserts may be in two pieces as shown in FIGS. 14 to 16, or may be joined in a single piece, as shown in FIGS. 17 and 18. With reference to FIG. 18, the insert 92 is arranged such that the upper surfaces 90 support the reinforcement mesh 88 substantially in line with an upper surface of the anchor 10.

FIGS. 19 a to 19 d show a chair 40 in accordance with a variation, wherein the chair 40 includes a plurality of support arms 94 for supporting a void former 96 mounted to the head portion 16 of the anchor 10. The support arms 94 support the void former 96 in such a way that the void former 96 can be removed from the chair 40 after casting of the concrete component, thereby leaving a void for inserting a lifting clutch through the eye of the head portion 16. FIGS. 20 a to 20 d show an alternative chair 40 which has support arms 94 configured to extend from the holders 80 for supporting the void former. FIGS. 21 a to 21 d show a further alternative chair 40 which has support arms 94 arranged to support the void former 96 at various locations at an underside of the void former 96.

Advantageously, this then does not place differential movement between the anchor and the void former through movement of the reinforcement mesh, as has occurred previously through the anchor body only being tied to the mesh via shear and tension bars. The chair provides direct localised support to the mesh at the anchor location and as such eliminates this differential movement whilst also eliminating the need for custom bent chairs under the anchor and under the mesh which all have different heights. The drawings show mesh supported as most common typical central mesh and then also supporting top mesh over the lifter in the case of two layers of mesh. In the case of two layers of mesh the bottom mesh is under the anchor and hence is not supported by the anchor—only the top mesh would be.

In previous systems, void formers are supported from the sideforms while the anchor body is connected to the mesh causing differential movement between the anchor body and void former including differential height placement and torsion between the two. This then results in movement away from the perfect design fit and causes poor clutch fit into the panel's edge in engagement with the anchor. This is currently a substantial problem in the industry. However, by supporting the anchor and void former together in perfect fit by the chair, this problem is eliminated.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word “comprise”, and variations such as “comprises” and “comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. 

1.-15. (canceled)
 16. A collar for an anchor for use in lifting a concrete component, said anchor comprising a head portion engageable with a clutch of a lifting system, and a body portion for embedment within the concrete component, the collar including an attachment portion for attaching the collar to the head portion of the anchor, and an abutment portion adapted to provide a clutch abutment surface for limiting rotation of the clutch relative to the anchor.
 17. A collar as claimed in claim 16, wherein when the collar is fitted to the anchor the abutment portion forms the clutch abutment surface as a shoulder adjacent the anchor.
 18. A collar as claimed in claim 17, wherein the clutch abutment surface is formed as a shoulder standing proud of the head portion for limiting rotation of the clutch about an eye of the head portion.
 19. A collar as claimed in claim 18, wherein the abutment portion provides a pair of opposed shoulders on the head portion for limiting rotation of the clutch about the eye in both directions of rotation.
 20. A collar as claimed in claim 19, including a gap between the shoulders which coincides with the eye of the head portion to allow passage of the clutch through the eye.
 21. A collar as claimed in claim 16, wherein the abutment portion is formed by an edge of the collar.
 22. A collar as claimed in claim 16, wherein the collar fits around the head portion, and is held to the head portion by way of a press fit.
 23. A collar as claimed in claim 16, wherein the collar is generally C-shaped.
 24. A collar as claimed in claim 16, including at least one shear bar attached to the collar.
 25. A collar as claimed in claim 24, wherein the shear bar engages in a groove of the collar.
 26. A collar as claimed in claim 24, wherein the shear bar is welded to the collar.
 27. A collar as claimed in claim 24, wherein the shear bar is formed in a generally wave-like shape, with oscillations in a direction generally perpendicular to a central axis of the anchor when the collar is fitted to the anchor.
 28. A collar as claimed in claim 27, including a second shear bar, wherein a major axis of the second shear bar is generally parallel to a major axis of the first shear bar and is substantially a mirror image of the first shear bar when viewed from an end of the anchor.
 29. An anchor for use in lifting a concrete component, said anchor comprising a single length of wire bent to form a head portion engageable with a clutch of a lifting system, and a body portion for embedment within the concrete component, wherein the anchor has a collar attached to the head portion to provide clutch abutment surfaces for limiting rotation of the clutch relative to the anchor, the collar being a collar as claimed in claim
 16. 30. An anchor system for use in lifting a concrete component, the assembly comprising an anchor formed from a one-piece elongate element shaped to form a head portion engageable by a clutch of a lifting system and a body portion for embedment within the concrete component; and a collar carried by the head portion of the anchor to define at least one clutch abutment surface for limiting rotation of the clutch relative to the anchor. 